The Kawai P 360 (or Kawai Digital Piano 360) was introduced in 1988. It has a wonderful hammer action keybed with 88 wooden keys and features 13 tones from Grand Piano to Brass and Strings.
For my social project I got a P 360 that had been used heavily as a theatre and pub piano resulting in a lot of dead keys and most of the selection buttons not working. It was unplayable and if you wanted to switch the tone/select another sound the corresponding button LED would just start blinking.
The P 360 has a built in function which allows for playing and sustaining one sound, switching to another, but you won't hear the new sound until all notes with the previous sound are released. So I suspected permanently triggering keys was the issue with the lost sound selection functionality.
There is just one screw both on the bottom left and right side to keep the top in place. Remove the screws and you can open it up.
Removing the keys
Unscrew the long batten on top of the keys first. Since the nuts are fixed with wax or glue you have to screw out the whole screw first, remove the nut with pliers and put the screw back in place.
Then remove all the springs. Pay attention to the different coloring of the springs! The silver springs are for white keys, while the slightly golden ones hold the black keys.
To take out a white key lift it up in the front and while enlarging the angle pull it softly upwards until it slips off its holding pin. To remove a black key you have to make some space first by removing a neighbored white one. Lift up the black key like a white one, then tilt it a bit aside and remove its hammer by pulling it backwards. This gives enough space to lift up the black key. Put the hammer back in place.
Remove the keybed circuit boards and wiring. Remove the rubber contact mats and keep track of their position and orientation on the board. Be careful to get rid of all dust with a vacuum cleaner. Clean all contacts both on the boards and mats softly and properly with benzine or something comparable, make sure the liqid evaporates traceless. Put the contact mats back in place and make sure they lay tight on the board. To push the nipples through the corresponding holes you can use a small Allen key. Be careful and use something that is not sharp, otherwise you will cut holes in the mat.
The contact concept Kawai used here is a bit different compared to keybeds produced nowadays. There is a circular contact area with a feathered spot in the middle and a ring all around. Velocitiy is determined by calculating the time between closing the center and the outer circuit.
Key fine tuning
Put all keys back in place and make sure to keep the order. Once the keybed is complete you want to do some trigger or pressure point fine tuning, to adjust dynamics and playability.
Each key has two screws to adjust the height of the key in the keybed (rear) and for dynamics (in the middle of the key). The dynamics screw enlarges contact pressure by turning it clockwise with a small screwdriver. So if a key is not responding fully to playing this might be the quick solution before opening up everything and giving it a complete cleaning.
On this P 360 some keys where triggering constantly so to get them all to the same level I turned all screws counterclockwise until the softest key touch would still make a sound. If a key was not adjusted like that I had a problem with repetition also. Playing/triggering the same key at a high repetition rate led to no-sound-at-all after a few hits.
I'm not sure yet how this tuning will work out in the long run since the keys ar wooden and wood "breathes" with humidity. So a readjustment might be necessary in summer, since I did this in dry winter air. I'll be writing an update if this is the case.
The P 360 was introduced before the general voltage in Europe was unified, unfortunately this piano was still set to 220 V (we have 230 V in Germany since 1993). But it is easily switched to 230/240 V by moving the corresponding fuse from the 220 V bracket to the 240 V bracket right next to it on the amp board (board to the left).
If you hear issues in sound like sizzling noise or unequal volume comparing left to right output, it's time to recap the boards. Replace all capacitors to their specification, like it's written on their bodies. Start on the amp board with the big ones and go for high quality caps here (Panasonic, Nichicon). It's good to keep that standard on the main board also, but you'd get away with cheaper ones.